How to assign values to variables in tableau

Question

I have a field named Datavalue 2, I have to manually assign value to that field, How do I write the calculations for this. Any leads for this will be helpful. Thanks in advance

Answer 1

• Tableau is a read-only tool. In order to make persistent modifications to the original source data, tableau does not allow.

• If you want to derive a value of a field that can change during the life of a Tableau visualization, but leave the original data source unchanged, that is entirely possible. 

• Calculated fields and parameters are the features of Tableau that help with this. Parameters can be set interactively by the user. Both features are documented in the on-line help.